Objective Measures of Functional Outcome in Recovery from Open Lower Limb Fractures – A Report from an Ortho-Plastic Research Clinic

BACKGROUND Open lower limb fractures are serious, potentially life-changing injuriesrequiring combined orthoplastic surgery and have significantly worse outcomes than similar closed fractures. There is little objective published data to determine which functional outcome measures best reflect progress or completeness of physical recovery. Our hypothesis was that objective measures combining strength, agility and balance would better reflect recovery than isolated parameters (e.g. range of motion) and would compare well to patients’ perceived recovery. METHODS Adultopen lower limb fracture patients were followed-up at 6 and 12 weeks, 6, 9 and 12 months post-injury. The mechanism,injurypattern, age, gender and treatment were recorded. Isolated parameter objective functional outcome measures (OFOMs)(range of movement and MRC strength grade) were compared to combined OFOMs(timed up and go (TUAG), comfortable and fast gait speed (CGS and FGS), Edgren Side Step Test(ESST) and Single Leg balance. Patient reported outcomes were recorded (Global Perceived Effect (GPE) scoreand Disability Rating Index (DRI)).

related improvements in combined OFOMs measuringmobility, strength, agility and balance paralleling patients' perception of recovery in the 12 months after open lower limb fractures. Over the same time-frame, the simple GPE score compared favourably with the DRI. Such parameters could become part of a defined core outcomes set. Focussing rehabilitation towards these combined OFOMs may help hasten recovery.

Trial registration
South West Wales REC 06/WMW02/10) Background Open lower limb fractures are serious and potentially life-changing injuries, often requiring combined orthopaedic and plastic surgical management in specialist units (1,2). Following surgery, rehabilitation to minimise swelling, scarring and promote independent mobility is vital. Even when the limb is preserved and wound and bone healing are complete, a wide range of clinical outcomes are seen, ranging from pain free mobility and a return to manual work, to ongoing pain, troublesome disfiguring scarring and problems with mobility. This distinguishes recovery from open lower limb fractures from their closed counterparts. Indeed, disability rating index (DRI) scores at 12 months post injury are distinctly worse in open fracture patients compared to those with closed fractures (3,4). For these reasons the need for a defined core outcome set for open lower limb fractures has been recognised (5). This would enable the meaningful comparison of surgical strategies within and between future studies.
In recent years, interest has grown in the value of Patient Reported Outcomes Measures (PROMS) as distinct from the measures of technical success such as wound or bone healing, alignment and the number and complexity of reconstructive surgical procedures. However, there is little objective published data to determine which functional outcome measures best reflect either patient progress or completeness of their physical recovery.
As part of a larger project studying recovery from open lower limb fractures, the potential benefits of functional recovery measures that reflect strength, agility and endurance became apparent (Wales Lower Limb Trauma Recovery Project (WaLLTR) South West Wales REC 06/WMW02/10). These 4 measures have been studied extensively in stroke rehabilitation, recovery from hip fracture and also sports medicine (6)(7)(8)(9). Given the paucity of data with respect to these combined measures in the open lower limb fracture population, a pragmatic decision was required to select a range of measures to be studied (10). Combined strength, agility and balance were determined as follows. The "Timed Up & Go" (TUG) Test was recorded as the time taken to stand up from a seated position in a chair, walk straight for 3 m, turn 180°, walk back to the chair, then sitting down (8). Completing this exercise in 10 seconds or less is regarded as normal mobility, 30 seconds or more reflecting significantly impaired mobility. The Comfortable Gait Speed (CGS) and Fast Gait Speed (FGS) were determined by measuring the walking speed in the middle 10 m of a 14 m straight line after asking the participant to "Walk at your preferred walking speed as if you were walking in a park" (CGS) and "Walk as fast and as safely as 5 you can" (FGS) respectively (7).

The Edgren Side
Step Test (ESST: metres) quantifies an individual's agility in the lateral direction.
Four cones are placed in a line each 1 m from its neighbour (9). The participant then side-steps back and forth to the outside cone as rapidly as possible for 10 seconds. Balance as a discrete parameter was assessed using the Single Leg Stand Test (SLS: seconds) (17). The length of time for which a participant balanced on the required leg (without the other lower limb touching and with their arms by their sides) was recorded, up to a maximum of 30 seconds.
The Global Perceived Effect score was recorded on a 0-100 mm linear scale, with none of their previous scores being visible to the patient. It was explained that the scale represented them at their very worst immediately following their injury (zero), to being restored to completely back to their former selves (100 mm) (18)(19)(20)(21).
The Disability Rating Index (DRI) was also recorded at each timepoint. The scale runs from 100 (worst) to zero (best); the minimum clinically important difference (MCID) in the DRI is 8 points (3,12) . These data were analysed in terms of data completeness and time related changes, in particular the number of individuals whose results had changed (improved or worsened) between measurements.

Results
In all, 79 patients enrolled although 2 patients subsequently withdrew their consent and a further 9 Patients' reported outcomes reflected in their GPE score and DRI also showed consistent improvement with time, as shown in Fig. 3. The DRI minimum detectable change has been recognised as +/-2.7 and so "no change" in this figure reflects responses within this range rather than being simply numerically equal. All but 2 patients DRI score had improved by the MCID of 8 + points between the baseline and 12 month assessments. However, the GPE score compared favourably with the DRI, with a higher proportion of improving responses at each time-point. 8 We hypothesised that improvements in objective outcome measures combining strength, agility and balance would mirror patients' own perceptions of their recovery after open lower limb fractures.

Discussion
There is a paucity of published data to establish reliable core clinical outcome measures in this group of patients (5,24). Open lower limb fractures can be life-changing injuries. Even when complication rates are low, a recent randomised multi-centre study has shown significant levels of patient reported disability throughout the first 12 months post-injury (3,25,26). In this study of 427 patients who completed the trial, DRI scores improved from the mid-sixties at 3 months to mid-forties at 12 months. By comparison, the DRI score of patients with closed distal tibial fractures were distinctly better with average scores in the low 20 s, around double the MCID for this measure (4).  (15). While the lunge weightbearing method to measure dorsiflexion may be very reliable (14), it cannot be used effectively in those unable to fully weight-bear. In this study, patients with articular fractures (AO 43B/C and AO 44 n = 22) were advised to be non-weight-bearing for 6 weeks and then incrementally increase to be fully weight-bearing by 12 weeks.
Gait speed is a recognised form of assessment in patients following stroke and hip fracture, with faster gait speeds associated with greater degrees of independence and mobility (27). Speeds greater than 1.2 m/s are considered normal, 0.8-1.2 m/s community ambulators, 0.4-0.8 m/s limited community ambulators and walking speeds lower than this leading to the patient essentially being housebound. In Fig. 2a it can be seen that by 9 months, approximately 75% of the patients completing the assessment were comfortable walking at a pace of 1 m/s or faster.
Comfortable and maximum gait speeds have been assessed in healthy individuals and stratified according to gender, height and age (7). Gender had little demonstrable effect, however gait speed did correlate with muscle strength, in particular hip abductors for comfortable gait speed and knee extensors for maximum gait speed. Comfortable gait speed declined slowly with increasing age from 20th to 70th decades (mean 1.4 m/s -1.3 m/s) and maximum gait speed more sharply (mean 2.5 m/s -1.9 m/s). In this study population, Fig. 2(b) shows that by 6 months approximately 75% of patients completing the assessment achieved a fast gait speed of 1 m/s or greater. By 12 months post injury, over half the patients could sustain a speed of 1.5 m/s. At 12 months, only 9 patients had TUAG times greater than 10 seconds, indicating normal mobility as determined by this test, although none exceeded 18 seconds.
In terms of patient reported outcome, the use of the GPE scale in the manner described yielded responses specific to the injury itself, inviting comparison of themselves at their worst immediately after injury versus how they were at their best beforehand. The responses elicited using the DRI gave medians comparable to those reported previously (approximately 60 at 3 months recovering to 40 at 12 months) but with a wide range of responses. The lack of consistent improvement with time for individual patients suggests that this score may be better restricted to studies of populations at defined and well separated timepoints, rather than being used as a "monitoring" score with serial measurements taken only a few months apart.
This study has limitations. Not all patients sustaining lower limb fractures will have been identified for potential enrolment. A very small proportion of those approached declined consent to attend the OPRC. Of those who did, few were able to attend every single appointment and so the data is inevitably incomplete. Nevertheless the results obtained are consistent across the population studied.
No comparison has been made with recovery in patients with comparable closed fracture types.
Available resources did not permit this, although the log-term goal of the project is to extend this approach to closed fracture patients. While such a comparison would have been of interest, published data and clinical experience would strongly suggest that these injuries are distinctly different in their outcomes, as well as surgical strategy {Costa, 2018 #52; Costa, 2017 #121}.
Determining outcomes in healthcare has moved beyond measuring the frequency of technical problems or achievements. Patients with deep infection or non-union after open fractures will require further management and so those complications may be better regarded not as outcomes, but events along the road to recovery. PROMS, even if derived from the specific patient population under review, will introduce an element of subjectivity. However patients' perception of their recovery is essential in completing the picture. Functional recovery is vital as this will determine independence, resumption of caring for their family and return to work, all of which are so important in sustaining an individual's self-worth. Identifying objective functional outcome measures which mirror patients' perception of recovery has great value in helping to focus rehabilitation and forming part of a set of core clinical outcomes for future research.
The ideal outcome measures for these severe (and indeed many less severe) injuries are yet to be determined. In a recent workshop involving patients, their family members, researchers and clinicians, walking ability/mobility was identified as a key outcome after open lower limb fractures (28). The objective measures described here were originally developed with patients whose mobility was impaired in mind. Further research is needed to refine these measures or develop new ones which reflect recovering mobility more precisely. In this way, a future core outcomes set will enable surgical strategies within and between studies to be meaningfully compared.

Declarations
Ethics approval was obtained prospectively (South West Wales REC 06/WMW02/10). No identifiable patient data or images are presented.
The datasets used and/or analysed during the current study are available from the corresponding 11 author on reasonable request.
The authors declare that they have no competing interests.
Funding was obtained from the AO Foundation and the Osteosynthesis and Trauma Care Foundation.
These funding bodies had no role in the design of the study, data collection, analysis, and interpretation nor did they have a role in writing the manuscript.
All of the authors contributed in terms of data collected, collation and preparation, and all contributed to the writing and review of the submitted manuscript.